# NixWRT - Using nix to build firmware images for consumer router hardware

**URL:** https://discourse.nixos.org/t/nixwrt-using-nix-to-build-firmware-images-for-consumer-router-hardware/203
**Category:** Announcements
**Created:** [May 13, 2018, 9:10pm UTC](https://discourse.nixos.org/t/nixwrt-using-nix-to-build-firmware-images-for-consumer-router-hardware/203 "2018-05-13T21:10:28Z")
**Posts on this page:** 1
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### Author: ![telent](https://discourse.nixos.org/user_avatar/discourse.nixos.org/telent/32/142_2.png) [@telent](https://discourse.nixos.org/u/telent)
#### Post date: [May 15, 2018, 8:15pm UTC](https://discourse.nixos.org/t/nixwrt-using-nix-to-build-firmware-images-for-consumer-router-hardware/203/6 "2018-05-15T20:15:14Z")

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`ls` says about 6.4MB for the full firmware image, comprising 2M for the kernel (hmm, not sure why that’s grown so large, it was 1.4MB or so last time I was paying attention) and the rest for the compressed root fs. It’s already using musl: I was [pleasantly surprised (bordering on stunned)](https://ww.telent.net/2018/2/28/musl_memory) to find how easy it was to switch.

```auto
[dan@loaclhost:/srv/media]$ ls -lh /tftp/    
-r--r--r-- 1 dan users 6.4M Jan 1 1970 firmware.bin                                     
-r--r--r-- 1 dan users 2.0M Jan 1 1970 kernel.image                                     
-r--r--r-- 1 dan users 4.3M Jan 1 1970 rootfs.image                                     

```

`firmware.bin` is the image you can actually flash: the separate kernel/rootfs files are development versions that can run entirely from RAM (if you have enough of it)

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